1. Field of Invention
This invention relates to switches. More specifically, the systems and methods of the invention relate to actuator systems and methods that may be used in a switch.
2. Description of Related Art
Micro-electromechanical (MEMS) technology switches are used in many applications. For example, a MEMS switch may be used in microfluidics to open and close a valve, or to direct a flow of fluid through a pipe. Optical communications systems may utilize large amounts of bandwidth. In order to improve efficiency, many optical communications systems utilize MEMS optical switches. The switches may be used in optical communications systems to control a lightwave through a waveguide or to add/drop channels in a multiplexer. For example, the optical switches may add or drop input signals from a fiber optic source to a different fiber optic output port sometimes using optical multiplexers. The optical switches may also include both a shuttle mechanism that holds a routing waveguide structure, and actuators that physically move the shuttle mechanism and a latching system.
Conventional optical switches typically use separate components for the optical switch and the optical switch actuator. The conventional shuttle mechanisms use thermally operated actuators, which operate in a two-dimension (2D) in-plane actuation motion to control the switching function within the optical communications systems. For example, when the shuttle mechanism forms the switching element, the thermal actuators are thermally driven to cause the shuttle mechanism to move between switching positions. However, this configuration requires that the thermal actuators overcome both a restoring force of the suspension arms of the shuttle mechanism, and the thermal actuator itself. Thus, high actuation forces and long displacement distances are required in order to adequately drive the shuttle mechanism. As a result, the long displacement distances require that long thermal actuators be used with optical switch. Accordingly, increased space within the switching system is required which can subsequently cause an increased tendency toward out of plane deformation within the optical switch.
Conventional out-of-plane magnetic and electrostatic actuators are used with MEM technology today. However, magnetic drives require using high-powered magnets in close proximity to the chip. This complex arrangement causes problems when packaging the chips because some components may need to be protected from the magnet. With lower strength magnets, very large currents are required to drive the actuators. Electrostatic actuators require large amounts of area on a chip, which increases the manufacturing costs. The electrostatic actuators are generally driven by high voltages, which preclude using them in application where high voltages are not available. Moreover, a “pull-in” instability existing in voltage-driven electrostatic actuators limits the controllable range of motion unless a complex drive circuitry is used, e.g., a switched capacitor charge drive circuitry.
Standard thermal bimorphs can create an out-of-plane motion for use in a switch. However, the bimorphs must be composed of two different materials, which result in different coefficients of thermal expansion for each material. Because MEMS processing involves various high-temperature steps, most bimorphs are formed with defects. The conventional systems discussed above may significantly increase the size of the overall chip, and increase manufacturing and packaging costs.